Socket for electrical parts

ABSTRACT

A socket for an electrical part comprises a socket body, a contact pin disposed to the socket body, a movable member mounted on the socket body and adapted to displace the contact pin, and an operation unit for moving the movable member to thereby displace the contact pin. When the contact pin is displaced, a terminal having a spherical outer shape of an electrical part is fitted to the socket body with the terminal being in non-contact state to clamping pieces of the contact pin and when the movable member is returned to an original position before movement therebetween, the displacement of the contact pin is released and the terminal of the electrical part contacts an contacting portion of a contact pin to thereby establish an electrical connection therebetween. The direction of the displacement of the contacting portion of the contact pin is set to a direction oblique to a moving direction of the movable member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a socket for electrical parts having animproved structure capable of detachably holding electrical parts suchas semiconductor devices, called hereinlater IC package(s).

2. Prior Art of the Invention

Sockets for electrical parts of the kinds mentioned above are known asdisclosed for example in Japanese Patent Publication No. HEI 3-66787. AnIC package mentioned herein as electrical part has an arrangement inwhich a number of IC leads project from a lower surface thereof in alattice arrangement having vertical rows Y and transverse rows X.

An IC socket, as a socket for electrical parts, for supporting such ICpackage and achieving electrical connection has a rectangular outerconfiguration formed of an electrically insulating material and isprovided with a substrate on which a cover is applied to be horizontallymovable to open or close the upper surface thereof.

The cover is formed with a number of through holes, corresponding to thelattice arrangement of the IC leads, through which a number of IC leadsare inserted, and these through holes, as insertion holes, provide aparallelogram shape in arrangement and the directions of the verticaland transverse rows of the leads are inclined by 45° with respect torespective sides of the cover configuration.

The substrate is formed with a number of contact groups in a latticearrangement corresponding to the IC leads and IC lead insertion holegroups.

When the cover is moved along a direction of one of diagonal lines ofthe lattice arrangement, the IC package mounted on the cover is alsomoved, whereby the respective IC leads and the contacts are separatedfrom or contacted to each other.

However, in such conventional arrangement, the IC lead insertion holegroups are inclined by 45° with respect to the rectangular configurationof the cover for ensuring displacement amount of the contacts which areseparated from or contacted to the IC leads, resulting in an enlargementof the cover and hence the device itself, thus providing a problem.

SUMMARY OF THE INVENTION

An object of the present invention is to substantially eliminate defectsor drawbacks encountered in the prior art described above and to providea socket for electrical parts capable of ensuring a displacement of acontact member such as contact pin and realizing a reduced entire size.

Another object of the present invention is to provide a socket for anelectrical part capable of achieving a wiping effect due to a contactingportion of a contact pin and suppressing a force directing obliquelyupward from acting on a terminal by reducing a vertical displacement ofan upper end of the contact pin.

A further object of the present invention is to provide a socket for anelectrical part capable of centering a position of a terminal of theelectrical part, when shifted, by a contact pin, and preventing theterminal from being applied by an desired force.

These and other objects can be achieved according to the presentinvention by providing a socket for an electrical part, which comprisesa socket body, a contact pin disposed to the socket body, a movablemember mounted on the socket body and adapted to displace the contactpin, and an operation member for moving the movable member to therebydisplace the contact pin, and in which when the contact pin isdisplaced, a terminal of an electrical part is fitted to the socket bodywith the terminal being in non-contact state to the contact pin and whenthe movable member is returned to an original position before movementthereof, the displacement of the contact pin is released and theterminal of the electrical part contacts an contacting portion of thecontact pin to thereby establish an electrical connection, wherein thedirection of the displacement of the contacting portion of the contactpin is set to a direction oblique to a moving direction of the movablemember.

In preferred embodiments, the contact pin is twisted by being pressed bythe movable member through which the contacting portion of the contactpin is displaced in the direction oblique to the moving direction of themovable member. The movable member is provided with a pressing portionpressing the contact pin and the pressing portion is formed obliquelywith respect to the moving direction of the movable member and thecontacting portion of the contact pin is moved parallelly in an obliquedirection with respect to the moving direction of the movable member bypressing the contact pin by the pressing portion.

The contact pin is composed of a plurality of clamping pieces betweenwhich the terminal of the electrical part is clamped, one of theclamping pieces being elastically deformable by a pressure of themovable member.

The terminal of the electrical part has preferably a spherical outershape.

In more detail in structure, there is provided a socket for anelectrical part, comprising:

a socket body;

a contact pin having a plurality of clamping pieces and disposed to thesocket body;

a movable member mounted on the socket body and adapted to displace thecontact pin; and

an operation member for moving the movable member to thereby displacethe contact pin,

the electrical part having a terminal having a spherical outer shape andbeing fitted to the socket body in a non-contact state to the contactpin through a displacement of the contact pin when the movable member ismoved, the displacement being released when the movable member isreturned to an original position before movement thereof to therebyestablish an electrical connection between the terminal and the contactpin, wherein the contacting portion of the contact pin is displaced bybeing twisted through the movement of the movable member in a directionoblique to a moving direction of the movable member.

According to the characters and structures of the present inventiondescribed above, the contacting portion of the contact pin is moved in adirection oblique to the moving direction of the movable member, so thatthe displacement amount of the contacting portion can be ensured, andmoreover, the orientation (X- and Y-directions) of the contactingportions of the contact pins are made coincident with the respectivesides of the socket for an electrical part having a rectangular outershape. As a result, the outer configuration of the socket for theelectrical part can be made compact in comparison with a conventionalstructure.

Furthermore, since the contact pin is twisted by being pressed by themovable member, the contacting portion of the contact pin is displacedin the direction oblique to the moving direction of the movable memberlikely in a manner to be rotatable, thus achieving the wiping effect,and moreover, the vertical displacement of the contact pin due to thetwisting motion thereof can be made small in comparison with aconventional flexible structure of the contact pin, whereby the obliquecontacting of the contact pin to the terminal can be suppressed and,hence, an upward force can be suppressed from acting on the terminal.

Still furthermore, the contact pin is provided with a plurality ofclamping pieces between which the terminal of the electrical part isclamped and one of these clamping pieces is elastically deformed by thepressure of the movable member, so that the terminal is clamped by thedeformable clamping piece even if the terminal is shifted in itsposition, whereby the centering of the terminal can be done by therespective clamping pieces and the acting of compulsory force on theterminal can be also prevented.

The nature and further characteristic features of the present inventionwill be made more clear from the following descriptions made withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view showing arrangement of a contact pin, asolder ball, etc. constituting a first embodiment of the presentinvention;

FIG. 2 is a plan view of an IC socket according to the first embodiment;

FIG. 3 is a front view of the IC socket according to the firstembodiment;

FIG. 4 is a sectional view of the IC socket of the first embodiment;

FIG. 5 is a right side view of the IC socket of the first embodiment;

FIGS. 6A and 6B are a plan view showing an arrangement of a through holeof an upper plate, the solder ball and the contact pin according to thefirst embodiment, in which FIG. 6A shows a state in which one ofclamping pieces of the contact pin is separated from the solder ball andFIG. 6B shows a state in which the solder ball is supported by bothclamping pieces of the contact pin;

FIGS. 7A and 7B are a sectional view concerning the state of FIG. 6, inwhich FIG. 7A is a sectional view taken along the line VIIA--VIIA inFIG. 6 and FIG. 7B is a sectional view taken along the line VIIB--VIIBin FIG. 6;

FIG. 8 is an illustration for explaining a function of the firstembodiment;

FIGS. 9A, 9B and 9C represents an IC package according to the firstembodiment, in which FIG. 9A is a front view of the IC package, FIG. 9Bis a bottom view thereof and FIG. 9C is a view showing an arrangement ofthe solder balls;

FIG. 10 is a plan view for explaining a function of a contact pin and asolder ball according to a second embodiment of the present invention;and

FIG. 11 is a perspective view representing a third embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[First Embodiment]

FIGS. 1 to 9 represent a first embodiment of the present invention, inwhich reference numeral 11 denotes an IC socket as a "socket forelectrical parts" and the IC socket 11 is a part for establishing anelectrical connection between a solder ball 12b as a "terminal" of an ICpackage 12 as electrical part and a print wiring board, not shown, of atester for carrying out a performance test of the IC package 12.

The IC package 12 is formed, as shown in FIG. 9, with a number of solderballs 12b projecting downward from the lower surface of an package body12a, and these solder balls 12b are arranged so as to provide a latticearrangement including vertical rows Y and transverse rows X. In thisembodiment, the IC package 12 has a thickness of 1.4 mm and each sidelength of 12 mm, and the solder balls 12b each has a diameter of 0.4 mmand are arranged with a pitch of about 0.8 mm.

The IC socket 11 has a socket body 13 to be mounted on a print wiringboard, and a rectangular movable plate 14 as a movable member isdisposed on the socket body 13 to be horizontally movable in theX-direction in a manner such that when the movable plate 14 ishorizontally moved, a contact pin 19 disposed on the socket body 13 iselastically deformed. An upper plate 16 is disposed above the movableplate 14 in a manner fixed to the socket body 13, and an upper operationmember 17 having a rectangular frame structure is disposed further abovethese elements to be vertically movable in a manner such that when theupper operation member 17 is vertically moved, the movable plate 14 ismoved in the horizontal direction through an X-shaped link 18.

In more detail, the contact pin 19 is composed of, for example, as shownin FIG. 1, an elongated member having an upper portion folded andseparated into a pair of clamping pieces 19a, 19b by which the solderball 12b is supported, and the contact pin 19 has springy property andelectrical conductivity.

The contact pin 19 has a lower portion press-fitted into the socket body13, as shown in FIG. 4, and lead elements 19c projects downward from thelower surface of the socket body 13, the lead elements 19c beingelectrically connected to the print wiring board. The clamping pieces19a, 19b of the contact pin 19 projecting upward over the upper surfaceof the socket body 13 are inserted into through holes 16b formed to themovable plate 14 and the upper plate 16 as shown in FIG. 7.

One 19a of the clamping pieces is provided with a portion 19d to bepressed by the movable plate 14 as shown in FIG. 1, and when thisportion 19d is pressed, it is twisted and a contacting portion 19e ofthe clamping piece 19a is rotated about a portion O in FIG. 8, wherebythe contact piece 19a is separated from or contacted to the solder ball12b. On the other hand, the other one 19b of the clamping pieces is notpressed by the movable plate 14 and is contacted to the solder ball 12bdue to its elastical property. These clamping pieces 19a and 19b arepositioned on opposing both sides of the solder ball 12b to therebyclamp the same in directions with angles of 45° with respect to thevertical rows Y and the transverse rows X of the arrangement of thesolder balls 12b. According to such arrangement, when the movable plate14 is moved along the X-direction, the moving direction of thecontacting portions 19e of one clamping piece 19a is set to a directionoblique to the moving direction of the movable plate 14.

Furthermore, the upper plate 16 has a rectangular shape having fourcorner portions to which recessed portions are formed, respectively, anda plurality of positioning bosses, not shown, projecting from the socketbody 13 are fitted to the recessed portions to thereby fix the upperplate 16 to the socket body 13 at the position above the movable plate14. The movable plate 14 is formed with insert portions through whichthe positioning bosses are idly inserted, the insert portion having asize allowing the movable plate 14 to be movable without interferingwith the positioning boss when the movable plate 14 is moved.

As shown in FIG. 6, the upper plate 16 is formed with a number ofthrough holes 16b, in a lattice arrangement of vertical and transverserows Y and X, into which the solder balls 12b of the IC package 12 areinserted. Each of the through hole 12b is composed of a circular portion16d into which the solder ball 12b is inserted, a first cutout portion16e into which the one 19a of clamping pieces is inserted and which isadapted to allow the displacement of the clamping piece 19a and a secondcutout portion 16f into which the other one 19b of clamping pieces isinserted and which is adapted to allow the displacement of the clampingpiece 19b. The circular portion 19d is formed to provide slightly largesize so as to handle the solder balls even if they have slightlydifferent diameters. Furthermore, as shown in FIGS. 2 and 4, the upperplate 16 is also formed with four projecting guide portions 16c, atportions corresponding to the respective four corner portions of the ICpackage, for positioning the IC package 12 when mounted to the upperplate 16.

Still furthermore, as shown in FIGS. 2 and 4, the upper operation member17 has a rectangular frame structure having an opening 17a having a sizecapable of being inserted with the IC package 12, which is insertedthrough this opening 17a and then mounted on the upper plate 16. Theupper operation member 17 is also disposed to the socket body 13 to bevertically movable through a slide portion 17b. As shown in FIGS. 3 and4, the upper operation member 17 is urged upward by means of spring 20disposed between this operation member 17 and the socket body 13.

Further, the X-shaped links 18 are disposed on both the side portions ofthe rectangular movable plate 14 along the transversely moving directionthereof to thereby constitute a toggle joint mechanism.

In more detail, each of the X-shaped links 18 has a first link member 23and a second link member 25 both having the same length as shown in FIG.3 and coupled together to be rotatable by means of a central couplingpin 27. The first link member 23 has a lower end portion 23a to beconnected to the lower end of the socket body 13 to be rotatable bymeans of a coupling pin 29, and the second link member 25 also has alower end portion 25a to be connected to one end portion of the sidesurface portion along the transversely moving direction of the movableplate to be rotatable by means of a lower end coupling pin 30. Thesefirst and second link members 23 and 25 have upper end portions 23b and25b which are connected to the upper operation member 17 by means ofupper end coupling pins 33 and 34, respectively. A long hole, i.e. slot,is formed to the upper end portion 23b of the first link member 23,which is connected to the upper operation plate 17 by means of the uppercoupling pin 33 through this slot.

A latch, not shown, is disposed to the socket body 13 so as to berotatable about an axis of the lower end portion thereof so that thelatch is engaged with or disengaged from the side edge portion of the ICpackage 12 set to a predetermined position and is urged by a spring inan engaging direction thereof. A cam portion is formed to the upperoperation member 17 to be slidable on the latch for rotating it in thedisengaging direction when lowered.

The IC socket 11 having the structure mentioned above will be used inthe following manner.

First, a plurality of IC sockets 11 are arranged on the print wiringboard by passing the lead portions 19c of the contact pins 19 of the ICsockets 11 through the insertion holes of the print wiring board andthen soldering the lead portions 19c thereto.

Next, the IC package 12 is set by, for example, an automatic machine tothe IC sockets 11 and electrically connected thereto in the followingmanner.

That is, the IC socket 11 is pressed downward by lowering the upperoperation member 17 against the urging force of the spring with the ICpackage 12 being supported. Then, the latch is rotated against theurging force of the spring through the engagement with the cam portionof the upper operation member 17, whereby the latch is retired from theinsertion area of the IC package 12. At the same time, the movable plate14 is horizontally moved through the X-links 18, and according to thishorizontal movement, the portion 19d of the one clamping piece 19a ofthe contact pin 19 is pressed by the pressing portion 14a of the movableplate 14 and then twisted to thereby rotate the contacting portion 19eabout the portion O in FIG. 8 in an arrowed direction, thus beingdisplaced. Under this state, when the IC package 12 is released from theautomatic machine, the solder ball 12b of the IC package 12 is insertedinto the through hole 16b of the upper plate 16. During the operationmentioned above, when the upper operation member 17 is lowered, theupper portions 23b and 25b of the respective link members 23 and 25 arepressed downward and lowered, thereby being rotated, and the lower endportion 25a of the second link member 25 is moved transversely (arroweddirection in FIG. 4), whereby the movable plate 14 is moved horizontallyin the X-direction.

Thereafter, when the pressing force of the upper operation member 17imparted by the automatic machine is released, the upper operationmember 17 is moved upward by the urging force of the spring 20 and themovable plate 14 returns to its original position. Then, one clampingpiece 19a of the contact pin 19 is returned by the elastical forcethereof. This clamping piece 19a and the contacting portion 19e contactthe solder ball 12b of the IC package 12 and the other clamping piece19b also contacts the solder ball 12b, thus establishing the electricalconnection with the solder ball 12b being supported by both the clampingpieces 19a and 19b.

At the same time, through the upward movement of the upper operationmember 17, the latch is rotated by the urging force of the spring andengages with the side portion of the IC package 12, thus holding the ICpackage 12.

In the structure mentioned above, since the contacting portion 19e ofthe contact pin 19 is moved obliquely with respect to the movingdirection (X) of the movable plate 14, the displacement amount of thecontacting portion 19e can be ensured. That is, in the case where thearrangement pitches in X- and Y-directions of the solder balls 12b aremade narrow, when the contacting portion 19e moves in the X- andY-directions, the displacement amount is made extremely short, whereas,when the displacing direction of the contacting portion 19e is inclinedby 45° with respect to the X- and Y-directions, so-called a dead spacecan be effectively utilized, thus ensuring the displacement amount.

Furthermore, since the contacting portion 19e of the contact pin 19 isconstructed to be obliquely movable with respect to the moving direction(X-direction) of the movable plate 14, the oriented directions (X- andY-directions) of the through hole groups 16b of the upper plate 16 canbe made along the respective sides of the IC socket 11 having therectangular outer shape. As a result, the outer configuration of the ICsocket 11 can be made compact in comparison with the conventional one.

Still furthermore, in this embodiment, since the one clamping piece 19aof the contact pin 19 is twisted and the contacting portion 19e is maderotatable about the portion O being the center of the rotation, thusachieving the wiping effect. Moreover, the structure of the clampingpiece 19a to be twisted makes it possible to make small the displacementamount in the vertical direction of the upper end of the clamping piece19a in comparison with the arrangement in which it is flexed in thearrowed direction P with the lower portion being the center as shown inFIG. 1, and hence, the solder ball 12b can be surely clamped. That is,in a case where the clamping piece 19a contacts the solder ball 12b inthe oblique state of the clamping piece 19a with large displacementamount, a force directing obliquely upward as shown by an arrow N inFIG. 1 acts on the solder ball 12b, and in such case, the solder ball12b may not be surely clamped. On the contrary, when the clamping piece19a is twisted, the displacement amount of the upper end thereof is madesmall, and since the clamping piece 19a is directed obliquely to therebysuppress the contacting thereof to the solder ball 12b, the solder ball12b can be surely clamped.

Still furthermore, since the solder ball 12b can be clamped andsupported from both side portions thereof by the elastically deformableclamping pieces 19a and 19b, even if the solder ball 12b is shifted inits position, the solder ball 12b can be clamped by the clamping pieces19a and 19b with the center of the solder ball being not shifted inposition, and moreover, since both the clamping pieces 19a and 19b areslightly displaceable, no compulsory force is applied to the solder ball12b. On the other hand, in the case where the solder ball is supportedby one 19a of the clamping piece and the inner wall surface of thethrough hole 16b of the upper plate 16, there may cause a case that acompulsory force will be applied to the solder ball when the solder ball12b is shifted in its position because the inner wall surface is notpositionally shifted.

[Second Embodiment]

FIG. 10 represents the second embodiment of the present invention, inwhich the contacting portion 19e of one 19a of the clamping pieces ismovable parallelly as shown in FIG. 10, whereas, in the firstembodiment, the clamping piece 19a is twisted. That is, the pressingportion 14a formed to the movable plate 14 has an inclination withrespect to the moving direction (X-direction) thereof, and when thepressing portion 14a is moved as shown in two-dot and dash-line in FIG.10, the contacting portion 19e is moved parallelly.

The structures other than the above are substantially the same as thoseof the first embodiment mentioned hereinbefore.

[Third Embodiment]

The third embodiment of the present invention will be describedhereunder with reference to FIG. 11. In the first and second embodimentsmentioned above, the present invention is applied to an IC socket 11 ofan open-top-type in which an electrical part is inserted through anopening formed to an upper surface of the socket as a socket forelectrical parts, whereas, in the third embodiment, the presentinvention is applied to an IC socket of so-called a clamshell type inwhich an electrical part is mounted on a rest plate and a lid is appliedto be rotatable from the upper side thereof to press downward theelectrical part.

That is, in the third embodiment, the movable plate 14 and an upperplate 41 are mounted to a socket body 38, and a lid 39 is disposed tothe upper surface of the upper plate 41 to be rotatable. The lid 39 has,in one side, a connection portion 37 which connects the movable plate 14and the upper plate 41 through a connecting portion 37 by means of acoupling pin 36. The other sides of the movable plate 14 and the upperplate 41 are connected through a link member 35 and a coupling pin 40.When the lid 39 is rotated, the movable plate 14 is moved horizontallywith respect to the socket body 38 through the operation of theconnecting portion 37 and the link member 35, and as like in the firstand second embodiments, the clamping piece 19a, not shown, of thecontact pin 19 is obliquely displaced with respect to the movingdirection (X-direction) of the movable plate 14. The operation andfunction other than the above are substantially the same as thosementioned with reference to the first and second embodiments.

It is to be noted that the present invention is not limited to thedescribed embodiments and many other changes and modifications may bemade without departing from the scopes of the appended claims.

For example, it is to be noted that although, in the respectiveembodiments mentioned above, the present invention is applied to an ICsocket as "socket for electrical parts", the present invention is notlimited to this and will be applicable to the other devices or the like.Furthermore, in the above embodiments, although a pair of clampingpieces are disposed to the contact pin to thereby clamp the terminal,i.e. solder ball, from both the sides, the terminal may be supported bycontacting the clamping piece only from one side. The terminal of anelectrical part to which the contact pin contacts is not limited to thespherical solder ball as mentioned above and may be formed as a rod-likemember.

What is claimed is:
 1. A socket for an electrical part, whichcomprises:a socket body, a contact pin disposed to the socket body, amovable member mounted on the socket body and adapted to displace thecontact pin, and an operation means for moving the movable member tothereby displace the contact pin, wherein said contact pin is twisted bybeing pressed by the movable member through which a contacting portionof the contact pin is displaced in a direction oblique to the movingdirection of the movable member, and in which when the contact pin isdisplaced, a terminal of an electrical part is fitted to the socket bodywith the terminal being in non-contact state to the contact pin and whenthe movable member is returned to an original position before movementthereof, the displacement of the contact pin is released and theterminal of the electrical part contacts a contacting portion of thecontact pin to thereby establish an electrical connection therebetween.2. A socket for an electrical part according to claim 1, wherein saidmovable member is provided with a pressing portion pressing the contactpin, said pressing portion being formed obliquely with respect to themoving direction of the movable member and said contacting portion ofthe contact pin is moved parallelly in an oblique direction with respectto the moving direction of the movable member by pressing the contactpin by the pressing portion of the movable member.
 3. A socket for anelectrical part according to claim 1, wherein said contact pin iscomposed of a plurality of clamping pieces between which the terminal ofthe electrical part is clamped, one of said clamping pieces beingelastically deformable by a pressure of the movable member.
 4. A socketfor an electrical part according to claim 1, wherein said terminal ofthe electrical part has a spherical outer shape.
 5. A socket for anelectrical part, comprising:a socket body; a contact means having apin-shape structure disposed to the socket body; a movable means mountedon the socket body and adapted to displace the contact means; and anoperation means for moving the movable means to thereby displace thecontact means, wherein said contact means is twisted by being pressed bythe movable member through which a contacting portion of the contactmeans is displaced in a direction oblique to the moving direction of themovable member, said electrical part having a terminal being fitted tothe socket body in a non-contact state to the contact means through adisplacement of the contact means when the movable means is moved, saiddisplacement being released when the movable means is returned to anoriginal position before movement thereof to thereby establish anelectrical connection between the terminal and the contact means,wherein said contacting portion of the contact means is displaced bybeing twisted through the movement of the movable member in a directionoblique to a moving direction of the movable member.